1. Field of the Invention
The present invention relates to a system that changes the magnification factor of an optical device based on the point of focus of a user, and more particularly to a system that changes the magnification factor by determining the intersection of gaze lines of the user.
2. Description of the Related Art
Optical devices such as binoculars and cameras often contain systems that can zoom in and zoom out to adjust the magnification of a viewed object. The systems incorporated into these devices change the magnification factor or zoom ratio by moving the zoom lens by either manual adjustment or by a motor. The motorized systems typically incorporate a dial or push button system or some other electronic control linked to the motor, such as a stepper motor, that moves the lenses to adjust the zoom ratio. By the push of a button a signal is sent to a control unit that activates the stepper motor. The stepper motor is mechanically linked to the lens system and adjusts the lenses to zoom in or zoom out at the control of the user. One particular manufacturer of motorized zoom lenses is Pelco, the operations and specifications of which can be viewed at their web site  less than  less than http://www.pelco.com greater than  greater than .
One problem of the existing motorized zoom lenses is that they all require the use of the hands of the user to control the zoom.
In a different field that is also related to the present invention, there are various techniques for tracking the direction of movement of the human eye, generally referred to as gaze tracking. Gaze tracking concerns detection or measurement of the angular movement and position of the eye. A document that describes various known gaze tracking techniques is Eye Controlled Media: Present and Future State, by Theo Engell-Nielsen and Arne John Glenstrup (1995), which may be found at  less than http://www.diku.dk/xcx9cpanic/eyegaze greater than  greater than , and is hereby incorporated herein by reference. The various techniques determine the focal point of a user by tracking the movements of the head and/or eyes of the user. The movement of an eye can be detected by use of the three present day techniques: detecting reflected light off of different parts of the eye, measuring electric potential differences of the adjacent skin as the eye moves, and utilizing specially designed contact lenses.
Commercially available gaze tracking systems determine the direction that a person is looking and then use the data regarding the gaze angle for a related purpose. For example, certain gaze tracking systems control the movement of a cursor on a computer screen based on where the person is looking. One manufacturer of gaze tracking systems is SensoMotoric Instruments, and their commercially available equipment may be seen at  less than  less than http://www.smi.de greater than  greater than . By mounting detectors, e.g. cameras and/or other sensors, onto or near the eyes of a user, the system detects the small angular movements of the eye and moves the cursor based on the angular movement of the eye. The SensoMotoric Instrument systems also disclose analysis of detected eye movement for medical diagnostic purposes.
Thus, gaze tracking systems have heretofore been limited in their applications to analysis of eye movement itself or to the simple application of moving a cursor such that it corresponds to the detected gaze angle of the eye.
It is an aspect of the present invention to provide a method and system for controlling a magnification factor of an optical device through use of a gaze tracking system.
It is another aspect of the present invention to additionally incorporate a voice recognition system to control basic functions of the zoom lens.
The invention comprises an optical device having a gaze tracking system that automatically adjusts an optical parameter based on a gaze distance parameter calculated using the gaze angle received from the gaze tracking system.
In one embodiment of the invention, an optical device comprises at least one adjustable optical element, gaze tracking input sensors, a motor that interfaces with the at least one optical element and is able to move the at least one element, and a control unit that supports gaze tracking and related gaze distance algorithms, as well as software that provides control input to the motor. The gaze tracking input sensors receive input regarding the gaze angle of the eyes, which is transmitted to the control unit. Gaze tracking algorithm in the control unit determines the gaze angle of the eyes, and gaze distance algorithm use the calculated gaze angle to calculate the gaze distance, that is, the distance from the viewer to the point where the eyes are focused or gazing. The calculated distance is then used to calculate an adjustment of the at least one optical element, and a control signal is sent to the motor to make the adjustment in position of the at least one optical element.
In another preferred embodiment, a pair of binoculars comprises zoom lenses, one or more gaze tracking cameras, a stepper motor that interfaces with the zoom lenses, and a control unit that supports gaze tracking and related gaze distance algorithms, as well as software that provides control input to the stepper motor. The gaze tracking cameras capture images of the position of one or more features of the eyes that is used by the gaze tracking algorithms in the control unit to determine the gaze angle of the eyes. The gaze angle is further processed by the gaze distance algorithm to determine the gaze distance. The gaze distance is further used to determine the appropriate position of the zoom lenses to focus at the gaze distance, and an appropriate control signal is provided by the processor to the stepper motor to move the zoom lenses to that position.
In yet another preferred embodiment, a camera comprises a zoom lens, one or more gaze tracking cameras, a stepper motor that interfaces with the zoom lens, and a control unit that supports gaze tracking and related gaze distance algorithms, as well as software that provides control input to the stepper motor. The gaze tracking cameras capture images of the position of one or more features of the eyes that is used by the gaze tracking algorithm in the control unit to determine the gaze angle of the eyes. The gaze angle is further processed by the gaze distance algorithm to determine the gaze distance. The gaze distance is further used to determine the appropriate position of the zoom lens to focus the camera at the gaze distance, and an appropriate control signal is provided by the processor to the stepper motor to move the zoom lens to that position.
Thus, among other things, the present invention provides an automatic adjustment to the optical element based on the gaze angle and corresponding focus point of the user. In addition, the present invention may additionally incorporate a voice recognition system whereby a voice command is required as input before the automatic adjustment is undertaken. For example, a voice command may be required before the gaze tracking algorithm and the subsequent processing and control of the optical element or lenses will be initiated. Alternatively, such processing may be engaged and running, but the final control command to the motor requires a voice input.